说明：  2PSK调制解调，先产生单极信号，再产生反码与之构成双极性码，然后加入载波信号，调制后加噪，通过低通滤波器后得到抽样判决后的波形
(In 2PSK modulation and demodulation, first the monopole signal is generated, then the inverse code is generated to form the bipolar code, then the carrier signal is added, then the noise is added after the modulation, and the waveform after the sampling decision is obtained through the low-pass filter)